This research project sought to evaluate long-term consequences of sport-related concussions (SRC) sustained during development on cardio-autonomic function. To do so, we compared the heart rate variability (HRV) of adolescents hockey players with a history of one or two sport-related concussion (HOC; n = 39) to the HRV of adolescents hockey players who never incurred a SRC (WHOC; n = 52). Athletes from the HOC group were 26 months (20) away from their last injury. Participants’ electrocardiogram was measured at rest, during and after an exercise session on ergocycle. The exercise session consisted of a 6 minutes incremental warm-up followed by 20 minutes between 60 and 70 % of maximal heart rate and finally a 2 minutes active cooldown. Then, a post-exercise rest of 10 minutes was completed. HRV linear and non-linear measures were calculated before, during and after the exercise session. Natural log of standard deviation of NN intervals (lnSDNN) and natural log of low frequencies (lnLF) were both higher for HOC group in the three conditions (rest, exercise, post-exercise) ( < 0.05). This difference was similar across all conditions. These results suggest that SRC might affect cardio-autonomic function differently during development than during adulthood thus reinforcing the need for specific post-concussion interventions for the developing population.